president’s address. 
131 
or in the Laminarian zone in many parts of our coast. The range 
of colour is very striking ; brown, red, blue, and green shades 
occurring in endless variety, some specimens being coloured in 
a uniform manner, whilst others are semi-transparent, with 
pigmented lines and other markings in different parts of their 
bodies. The phenomenon of protective coloration is very con- 
spicuously seen, the individuals commonly harmonising to 
a remarkable extent with their surroundings. The species is of 
very sedentary habits, and “ its prime object in life is to anchor 
itself” to some seaweed or other object which it commonly matches 
in colour. 
Messrs. Gamble and Keeble have carried on a careful and 
elaborate series of observations with the object of ascertaining the 
real facts with regard to the colour-changes. They find that 
immature specimens show the most remarkable colours and 
resemblance to their surroundings ; and that the females not only 
have more elaborate patterns than the males, but are “ more 
resourceful” in adapting themselves to their surroundings than are 
the members of the other sex. It is suggested that this difference 
is perhaps correlated with the more sluggish habits of the female, 
which is usually burdened with a load of eggs or developing larvae, 
and has therefore more need of protective coloration than the 
male. A number of Hippolyie of different colours were placed 
in a dish, to which a selection of sea-weeds was then added. 
After a time they were found to have matched themselves with 
remarkable accuracy to the sea-weeds, each colour-variety de- 
liberately selecting a sea-weed which it resembled in tint. "When 
an individual is placed with a weed of a new colour, it is slow to 
respond to its altered environment. Green specimens placed with 
brown weed were found to retain their green colour, even for 
a week or more, although in the end they adopted a brown tint. 
The recovery to green was more rapid when they were again placed 
with green weed. It thus appears that the resemblance between 
the prawn and its environment is not due to any power possessed 
by the Hippolyte of adapting itself rapidly to its surroundings. 
Each individ-oal seems to remain in the environment which 
VOL. 711. 
K 
